Pipeline irrigation pipe diameter optimization method based on small electromechanical canal irrigation area system layout

Abstract

The invention discloses a pipeline irrigation pipe diameter optimization method based on a small electromechanical channel irrigation area system layout, which comprises the following steps of: determining the total pressure of a pipe network by taking the total lift of open channel irrigation as a reference according to the requirement that the designed total lift of a pipeline irrigation system does not exceed a certain multiple of the total lift of the open channel irrigation system; an orthogonal design method is adopted, and the total pressure of the pipe network is distributed in all levels of pipe networks; according to the pressure distributed by each level of pipe network, the pipe diameter of the pipe network in each row of the orthogonal table and the pipe network project investment are deduced; and through orthogonal analysis, the minimum pipe network investment is determined, and the pipe diameters of the corresponding stages of pipelines are determined. The design reasonability and practicability of the pipeline irrigation system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of irrigation and drainage, and in particular to a method for optimizing the diameter of irrigation pipes based on the layout of a small electromechanical canal irrigation system. Background Art

[0002] Extensive experimental data and practical experience demonstrate that compared to open channel irrigation, pipe irrigation offers significant advantages, including water conservation, land conservation, increased production, labor-saving and time-saving, rapid water delivery, timely water supply, and labor-saving management. Compared to sprinkler and micro-irrigation, it also boasts lower investment and operating costs and energy savings. Consequently, pipe irrigation is increasingly being adopted for high-standard farmland renovation. In some irrigation areas previously irrigated with open channels, the transition from unpressurized flow to pressurized flow with pipe irrigation results in a significant increase in lift, exponentially increasing water extraction costs. Flow rate selection is the most critical factor influencing lift. The traditional pipe irrigation method suffers from the following drawbacks: first, pipe diameter is determined based on pipe flow and economic flow rate; then, flow rates and loss heads are recursively calculated at each level; and finally, pump selection is based on pipe flow and head. Because this method cannot predict the increase in water extraction costs after converting from open channel irrigation to pipe irrigation, improper selection of parameters such as flow rate often leads to a significant increase in system operating energy costs, resulting in resistance from water users and even requiring a complete redesign. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a method for optimizing the diameter of pipe irrigation pipes based on the layout of a small electromechanical canal irrigation system, so as to overcome the drawbacks of the traditional design method of using economic flow rate to calculate the pipe diameter, which leads to unreasonable pipe diameter selection, excessive pipe head and high water lifting costs.

[0004] Technical solution: A method for optimizing pipe diameters for irrigation pipes based on the layout of a small electromechanical canal irrigation system, comprising the following steps:

[0005] S1: Determine the pump flow and pump head for the irrigation area based on the irrigation area, irrigation rate, irrigation water utilization coefficient and open channel irrigation system layout;

[0006] S2: Select the water pump and power configuration based on the pump flow and pump head of the open channel irrigation system; and determine the actual head, flow and efficiency of the water pump of the open channel irrigation system;

[0007] S3: Based on the actual pump head and flow rate for open channel irrigation and the cost increase limit for pipe irrigation, the preliminary estimate of the pipe irrigation head is made. The total design pressure of the pipe network system is then inferred based on the water level of the inlet tank and the field elevation.

[0008] According to the total design pressure of the pipe network, the orthogonal design method is used to discretize the pressure of each level of the pipe network; and the pipe diameter of the pipe network is calculated based on the pressure allocated to each level of the pipe network;

[0009] S4: Calculate the pipe network investment under each combination based on the standard pipe diameters at each level. Calculate the head for pipe irrigation using the pipe diameters at each level that minimize the pipe network investment. Finally, select the pump and power configuration.

[0010] S5, calculate the water lifting cost based on the flow rate, head, and pump efficiency during pipe irrigation, and compare it with the water lifting cost during open channel irrigation. If the requirements are met, the selected pipe diameter is used as the pipe diameter for pipe irrigation; if the requirements are not met, select the calculated results of the pipe diameters of each level corresponding to the next smallest value of the pipe network project investment, and repeat steps S3 and S4 until the requirements are met.

[0011] Furthermore, by collecting the irrigation area A, irrigation rate q, irrigation water utilization coefficient η 水 , determine the pump flow rate Q of each irrigation area 选泵 :

[0012]

[0013] According to the layout of the open channel irrigation channel system, the water level of the irrigation area inlet pool H 进 , field ground elevation 田 Calculate the water level H of the water pump out of the pool during open channel irrigation 出 Select pump head H 选泵 :

[0014]

[0015] H 选泵 =1.25(H 出 -H 进 )

[0016] Among them, ∑Li is the sum of the losses along the open channel, It is the sum of local losses in the open channel.

[0017] Furthermore, in step S3, the steps for solving the pipe diameter of the pipe network are as follows:

[0018] S31, calculate the total pressure of the pipe network system;

[0019] The total cost of pipe irrigation does not exceed k times the total cost of canal irrigation, and the total head of pipe irrigation does not exceed the head H of canal irrigation. 渠，泵 k times, the calculation formula for the total head of pipeline irrigation is as follows:

[0020] H 管，总 =kH 渠，泵 -H 泵损 -C=kH 渠，泵 -1.25(H 出 -H 进 -▽管网埋深 )-C

[0021] Among them, H 管，总 is the total head of pipeline irrigation; C is the outlet pressure of the pipe network, in m; H 泵损 is the water pump head loss, ▽ 管网埋深 The buried depth of the pipe network;

[0022] S32, distributes the pressure of pipe network at all levels;

[0023] Assume that the pressure distribution coefficient of each level of pipe network is λ i ,i=1,2,3, and

[0024] S33, discretize the pressure coefficients of each level of the pipe network and construct a three-factor, three-level orthogonal test table;

[0025] S34, according to the orthogonal test table, the pressure distribution of each row is calculated, and the total head H of the pipe irrigation is calculated. 管，总 Make an allocation;

[0026] And calculate the pipe diameters of each level of pipe network:

[0027]

[0028] Where, d 计算 is the inner diameter of the pipe, in meters; f is the friction coefficient of the pipe; L is the length of the pipe, in meters; Q is the flow rate of the pipe, in meters 3 / h; n is the flow index; F is the multi-port coefficient; h p is the outlet working pressure, in m; ΔZ is the height of the impact of terrain undulation on the outlet of the pipe network, in m; the value of b is related to the material;

[0029] S35, selecting a standard pipe diameter based on the calculated pipe inner diameter.

[0030] Further, when the orthogonal test table does not satisfy When the requirement is met, normalize each row in the table.

[0031] Furthermore, in step S5, the following formula is used to calculate the ratio of water pump energy consumption during pipe irrigation and canal irrigation:

[0032]

[0033] Where γ is the water density, unit is g / cm 3 , Q 管，泵 The water pump flow rate during pipe irrigation, in m 3 / s;H 管，泵 is the water pump head for pipe irrigation, in m; η 管，泵is the pump efficiency in pipe irrigation; Q 渠，泵 is the water pump flow rate during channel irrigation, in m 3 / s;H 渠，泵 is the pump head for canal irrigation, in m; η 渠，泵 is the pump efficiency during canal irrigation; k is the limit number required for the ratio of pipe irrigation cost to open channel irrigation cost;

[0034] When the cost of pipe irrigation is less than k times the cost of open channel irrigation, the calculation result is the pipe diameter of the pipe irrigation.

[0035] Compared with the prior art, the present invention has the following significant effects:

[0036] The present invention uses the total head of open channel irrigation as a benchmark and determines the total pressure of the pipe network based on the requirement that the total head of the pipe irrigation system design does not exceed a certain multiple of the total head of the open channel irrigation system. The orthogonal design method is used to distribute the total pressure of the pipe network among each level of the pipe network. Based on the pressure distributed to each level of the pipe network, the pipe network diameters and pipe network project investment in each row of the orthogonal table are deduced. Through orthogonal analysis, the minimum pipe network investment is determined, and the corresponding pipe diameters for each level are determined. This invention can control the total head increase during pipe irrigation within an allowable range, overcoming the drawbacks of traditional pipe irrigation system design, which involves calculating pipe diameters based on economic flow rates, resulting in irrational pipe diameter selection, excessive pipe network head, and excessive water lifting costs. This improves the rationality and practicality of pipe irrigation system design. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a flow chart of the present invention;

[0038] Figure 2 This is the layout diagram of the irrigation system in the irrigation area. DETAILED DESCRIPTION

[0039] The present invention will be described in further detail below with reference to the accompanying drawings and specific implementations.

[0040] The present invention provides a method for optimizing pipe diameters in pipe irrigation areas based on the layout of a small electromechanical canal irrigation area system. Figure 1 As shown, the following steps are included:

[0041] Step 1: Collect the irrigation area, determine the irrigation rate, clarify the irrigation water utilization coefficient of the irrigation area, and determine the pump flow rate of the irrigation area.

[0042] According to the layout of the open channel irrigation system, the water level of the irrigation area inlet pool, the field ground elevation, etc. are collected to calculate the pump head for open channel irrigation.

[0043] Collect the irrigation area A, irrigation rate q, and irrigation water utilization coefficient η of the irrigation area 水 , determine the design irrigation flow Q of each irrigation area选泵 (as pre-selected pump flow):

[0044]

[0045] According to the water level H of the irrigation area inlet pool 进 , field ground elevation 田 , use formula (2) and (3) to calculate the water level H of the water pump out of the pool 出 Select pump head H 选泵 :

[0046]

[0047] H 选泵 =1.25(H 出 -H 进 ) (3)

[0048] Among them, ∑Li is the sum of the losses along the open channel, It is the sum of local losses in the open channel.

[0049] Step 2: Select the pump and power configuration according to the pump flow and pump head of the open channel irrigation system; and deduce the actual pump head H of the open channel irrigation system under the conditions of the pump and power configuration. 渠，泵 , flow Q 渠，泵 and efficiency η 渠，泵 .

[0050] Step 3: Based on the actual head and flow during open channel irrigation and the cost increase limit of pipe irrigation required by the design, the head during pipe irrigation is initially estimated, and the total design pressure of the pipe network system is reversed based on the water level of the water inlet pool and the field elevation.

[0051] According to the total design pressure of the pipeline network, the orthogonal design method is used to discretize the pressure of each level of the pipeline network, and according to the pressure allocated to each level of the pipeline network, the pipeline diameter is deduced and converted into the standard pipe diameter.

[0052] Step 31: Calculate the total pressure of the pipe network system.

[0053] The irrigation area adopts pipe irrigation, so that the total cost of pipe irrigation does not exceed k times the total cost of channel irrigation. Then the total head of pipe irrigation does not exceed the head H of channel irrigation. 渠，泵 k times; C is the outlet pressure of the pipeline network, the unit is m.

[0054] H 管，总 =kH 渠，泵 -H 泵损 -C=kH 渠，泵 -1.25(H 出 -H 进 -▽ 管网埋深 )-C (4)

[0055] Among them, H 管，总 is the total head of pipeline irrigation; H 泵损 is the water pump head loss; 管网埋深 is the buried depth of the pipe network. In this implementation, it is taken as 0.8m below the ground surface;

[0056] Step 32: Allocate pressure to each level of the pipeline network.

[0057] Assume that the pressure distribution coefficient of each level of pipe network is λ i ,i=1,2,3, and

[0058] Step 33: Discretize the pressure coefficients of each level of the pipe network, and discretize λ1 into λ 11 ,λ 12 ,λ 13 ,λ2 is discretized intoλ 21 ,λ 22 ,λ 23 ,λ3 is discretized intoλ 31 ,λ 32 ,λ 33 , construct a three-factor, three-level orthogonal test table (see Table 1).

[0059] Table 1 Three-factor, three-level orthogonal test table

[0060]

[0061] Because each row of the above orthogonal table does not necessarily satisfy Therefore, each row of the above table is normalized and the orthogonal test table after processing is (see Table 2).

[0062] Table 2 Improved three-factor, three-level orthogonal test table

[0063]

[0064] Step 34: According to the pressure distribution ratio of each row in Table 2, 管，总 Make an allocation;

[0065] And calculate the pipe diameters of each level of pipe network:

[0066]

[0067] Where, d 计算 is the inner diameter of the pipe, in meters; f is the friction coefficient of the pipe; L is the length of the pipe, in meters; Q is the flow rate of the pipe, in meters 3 / h; n is the flow index; F is the multi-port coefficient; h pis the outlet working pressure, in m; ΔZ is the height of the impact of terrain undulation on the outlet of the pipe network, in m; the value of b is related to the material, and in this embodiment, b=4.77.

[0068] Step 35, based on the calculated d 计算 As a result, the standard pipe diameter d is selected 标准 .

[0069] Step 4: Calculate the pipeline network project investment for each row in the orthogonal table 2 based on the standard pipe diameters of each level of pipeline network;

[0070] Perform orthogonal analysis on the orthogonal table to determine the pipe diameters at each level; according to the analysis results, the standard pipe diameters d at each level are 标准 Re-substitute the pipe irrigation system for verification; re-select the pump and distribute the flow and pressure of each level of pipe according to the selected pump.

[0071] Step 5: Calculate the water lifting cost based on the flow rate, head, and pump efficiency of the pipeline irrigation after the reselected pump, and compare it with the water lifting cost of open channel irrigation. If the requirements are met, the selected pipe diameter is the required one.

[0072] The following formula is used to calculate the ratio of water pump energy consumption in pipe irrigation and channel irrigation:

[0073]

[0074] Where γ is the water density, unit is g / cm 3 , Q 管，泵 The water pump flow rate during pipe irrigation, in m 3 / s;H 管，泵 is the water pump head for pipe irrigation, in m; η 管，泵 is the pump efficiency in pipe irrigation; Q 渠，泵 is the water pump flow rate during channel irrigation, in m 3 / s;H 渠，泵 is the pump head for canal irrigation, in m; η 渠，泵 is the pump efficiency in canal irrigation; k is the limit number required for the ratio of pipe irrigation cost to open channel irrigation cost.

[0075] When the cost of pipe irrigation is less than k times the cost of open channel irrigation, the calculation result is what we want.

[0076] If the requirements of formula (6) are not met, the calculated results of the pipe diameters of each level corresponding to the second-ranked pipe network project investment in the orthogonal analysis results are selected, and steps 4 and 5 are repeated until the requirements are met. This is to reduce project investment costs, ensure the smooth operation of the pipe irrigation area, and provide a basis for the transformation of small electromechanical canal irrigation areas into pipe irrigation areas.

[0077] In this embodiment, taking an irrigation district in Jiangsu as an example, the detailed implementation steps are as follows:

[0078] Step A1, collected basic information about an irrigation district in Jiangsu;

[0079] The irrigation area is 200 mu, the farmland ground elevation is about 3.5m, and the water source is at a constant level of 1.0m. The original irrigation was done by open channel, and a pipeline irrigation system is planned to be built, using a pump station to pump water. PE pipes are used as pipe materials; the pipeline layout is as follows Figure 2 As shown: From the pump station outlet to the south along the direction of the field, the main pipe and branch pipe are arranged. The length of each level of pipe is shown in Table 3. The pipe is buried 0.8m underground. A water outlet is set every 30m on the branch pipe. It uses PE pipe and is 0.3m above the ground. The irrigation design guarantee rate of the irrigation area is 95%, and the irrigation rate is 7.63m. 3 / s / 10,000 mu, irrigation water utilization coefficient 0.85, the unit price of pipes of various specifications is shown in Table 4. The overall layout is shown in Figure 2 .

[0080] The irrigation area is divided into two groups of rotation irrigation, including:

[0081] Rotation irrigation group 1: branch pipe 1 (controls agricultural pipe 1 and agricultural pipe 2).

[0082] Rotation irrigation group 2: branch pipe 2 (controls agricultural pipe 3 and agricultural pipe 4).

[0083] Table 3 Irrigation area control area

[0084]

[0085] The unit price of pipes is shown in Table 4 below.

[0086] Table 4 Pipe unit price list

[0087]

[0088] Calculate the flow rate of selected pumps in the irrigation area:

[0089]

[0090] Calculate the pool water level and select the pump head:

[0091]

[0092] H 选泵 =1.25(H 出 -H 进 )=1.25×(4.21-1.0)=3.70m

[0093] Step A2, select a pump;

[0094] Select one 250HW-5 water pump with a head of 3.7m and a flow rate of 646m 3 / s, device efficiency 84%.

[0095] Step A3, calculating the total pressure of the pipe network and distributing it;

[0096] According to the survey, the total pressure of the pipe irrigation system does not exceed 1.5 times the total head of the open channel. The outlet pressure C of the pipe network is 0.5m, so the total pressure of the pipe network is:

[0097] H 管，总 =kH 渠，泵 -H 泵损 -C=1.5×3.7-1.25(3.5-1.0-0.8)-0.5=2.95m

[0098] Small electromechanical irrigation areas generally have a three-level pipe network. Based on experience, the proportion of each level of pipe network to the total pressure is discretized to 0.3, 0.5, and 0.7 respectively, and an orthogonal table is constructed (see Table 5).

[0099] Table 5 Normalized processing of the balanced test collocation table

[0100]

[0101] Step A4: Calculate the pipe diameters at all levels and make an investment estimate;

[0102] 1) According to Table 5, taking the most unfavorable pipeline network line (1-2-3-branch 3) as an example, the pipe diameter is calculated and converted into the standard pipe diameter, and the investment is estimated. The total investment for each level of pipeline diameter is shown in Table 6.

[0103] Table 6 Total investment for pipeline diameters at all levels

[0104]

[0105] 2) Conduct orthogonal analysis to determine the pipe diameters at each level of the pipeline network: 400mm / 23.7mm for main pipes, 315mm / 18.7mm for branch pipes, and 250mm / 14.8mm for agricultural pipes.

[0106] Step A5, verification.

[0107] Substituting the minimum piping project investment and checking, the lift can be obtained as:

[0108] H 管，总 =0.5+0.3+0.8+2.76+(3.5-0.8-1.0)×1.25=4.79m

[0109] Reselect the pump, select a pump head of 4.79m and a pump flow of 646m 3 / s, using a 300HW-5 water pump with a head of 5.5m and a flow rate of 646m 3 / s, device efficiency 84%.

[0110] Verification:

[0111]

[0112] Conclusion: meets the requirements.

[0113] In summary, the method for optimizing and determining pipe diameters in pipe irrigation areas of the present invention overcomes the drawbacks of unreasonable pipe diameter selection, excessive pipe head, and high water lifting costs caused by calculating pipe diameters based on economic flow rates, and provides a basis for determining pipe diameters in pipe irrigation areas based on the layout of open channel irrigation systems.

Claims

1. A method for optimizing pipe diameter for irrigation pipes based on the layout of a small electromechanical canal irrigation system, characterized in that: The following steps are involved: S1: Determine the pump flow and pump head for the irrigation area based on the irrigation area, irrigation rate, irrigation water utilization coefficient and open channel irrigation system layout; S2: Select the water pump and power configuration based on the pump flow and pump head of the open channel irrigation system; and determine the actual head, flow and efficiency of the water pump of the open channel irrigation system; S3: Based on the actual pump head and flow rate for open channel irrigation and the cost increase limit for pipe irrigation, the preliminary estimate of the pipe irrigation head is made. The total design pressure of the pipe network system is then inferred based on the water level of the inlet tank and the field elevation. According to the total design pressure of the pipe network, the orthogonal design method is used to discretize the pressure of each level of the pipe network; and the pipe diameter of the pipe network is calculated based on the pressure allocated to each level of the pipe network; S4: Calculate the pipe network investment under each combination based on the standard pipe diameters at each level. Calculate the head for pipe irrigation using the pipe diameters at each level that minimize the pipe network investment. Finally, select the pump and power configuration. S5, calculate the water lifting cost based on the flow rate, head, and pump efficiency during pipe irrigation, and compare it with the water lifting cost during open channel irrigation. If the requirements are met, the selected pipe diameter is used as the pipe diameter for pipe irrigation; if the requirements are not met, select the calculated results of the pipe diameters of each level corresponding to the next smallest value of the pipe network project investment, and repeat steps S3 and S4 until the requirements are met.

2. The method for optimizing the diameter of irrigation pipes based on the layout of a small electromechanical canal irrigation system according to claim 1, characterized in that: By collecting the irrigation area A, irrigation rate q, irrigation water utilization coefficient η 水 , determine the pump flow rate Q of each irrigation area 选泵 : According to the layout of the open channel irrigation system, the water level of the irrigation area inlet pool is collected. 进 , field ground elevation Calculate the water level H of the water pump outlet pool during open channel irrigation 出 Select pump head H 选泵 : H 选泵 =1.25(H 出 -H 进 ) Among them, ∑Li is the sum of the losses along the open channel, It is the sum of local losses in the open channel.

3. The method for optimizing the diameter of irrigation pipes based on the layout of a small electromechanical canal irrigation system according to claim 1, characterized in that: In step S3, the steps for solving the pipe network diameter are as follows: S31, calculate the total pressure of the pipe network system; The total cost of pipe irrigation does not exceed k times the total cost of canal irrigation, and the total head of pipe irrigation does not exceed the head H of canal irrigation. 渠，泵 k times, the calculation formula for the total head of pipeline irrigation is as follows: Among them, H 管，总 is the total head of pipeline irrigation; C is the outlet pressure of the pipe network, in m; H 泵损 is the pump head loss, The buried depth of the pipe network; S32, distributes the pressure of pipe network at all levels; Assume that the pressure distribution coefficient of each level of pipe network is λ i ,i=1,2,3, and S33, discretize the pressure coefficients of each level of the pipe network and construct a three-factor, three-level orthogonal test table; S34, according to the orthogonal test table, the pressure distribution of each row is calculated, and the total head H of the pipe irrigation is calculated. 管，总 Make an allocation; And calculate the pipe diameters of each level of pipe network: Where, d 计算 is the inner diameter of the pipe, in meters; f is the friction coefficient of the pipe; L is the length of the pipe, in meters; Q is the flow rate of the pipe, in meters 3 / h; n is the flow index; F is the multi-port coefficient; h p is the outlet working pressure, in m; ΔZ is the height of the impact of terrain undulation on the outlet of the pipe network, in m; the value of b is related to the material; S35, selecting a standard pipe diameter based on the calculated pipe inner diameter.

4. The method for optimizing pipe diameter for irrigation based on the layout of a small electromechanical canal irrigation system according to claim 3, characterized in that: When the orthogonal test table does not satisfy When the requirement is met, normalize each row in the table.

5. The method for optimizing the diameter of irrigation pipes based on the layout of a small electromechanical canal irrigation system according to claim 1, characterized in that: In step S5, the following formula is used to calculate the ratio of water pump energy consumption during pipe irrigation and canal irrigation: Where γ is the water density, unit is g / cm 3 , Q 管，泵 The water pump flow rate during pipe irrigation, in m 3 / s;H 管，泵 is the water pump head for pipe irrigation, in m; η 管，泵 is the pump efficiency in pipe irrigation; Q 渠，泵 is the water pump flow rate during channel irrigation, in m 3 / s;H 渠，泵 is the water pump head during canal irrigation, in m; η 渠，泵 is the pump efficiency during canal irrigation; k is the limit number required for the ratio of pipe irrigation cost to open channel irrigation cost; When the cost of pipe irrigation is less than k times the cost of open channel irrigation, the calculation result is the pipe diameter of the pipe irrigation.

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